Suspected US drones have killed 11 alleged al-Qaida militants in a strike in southern Yemen, local military authorities have said.

The first of the two attacks took place on Saturday near the border of Marib and Shabwa provinces southeast of the capital, Sana'a, killing six militants, including one Egyptian national, the Yemeni officials said. A second strike hit two cars in Marib, killing a further five al-Qaida-linked fighters.

The air strikes come a week after the US took out a top al-Qaida operative wanted over the 2000 bombing of USS Cole in a similar missile attack from an unmanned aircraft.

It also follows a warning just a few days ago from the former head of the CIA's counter-terrorism unit, Robert Grenier, over the excessive use of drones. He said the policy risks turning Yemen into the "Arabian equivalent of Waziristan" – a reference to the strife-torn Pakistani region.

There was no immediate confirmation from the US on whether Washington was behind Saturday's attacks.

Yemeni officials have reported more frequent American drone strikes since Yemen's new president, Abed Rabbo Mansour Hadi, took power in February vowing to ramp up the fight against al-Qaida militants.

The Pentagon recently sent American military trainers to Yemen, and Washington has spent hundreds of millions of dollars assisting the impoverished Arab nation against al-Qaida and other extremist groups in the country.

Experts say al-Qaida in the Arabian Peninsula (AQAP), is one of the most dangerous offshoots of the terror network.

Yemen was the launching pad for two foiled al-Qaida attacks on US territory: the Christmas 2009 attempt to down an American airliner over Detroit with an underwear bomb, and the sending of printer cartridges packed with explosives to Chicago-area synagogues in 2010.

On Monday, it was disclosed that the CIA thwarted yet another plot by AQAP to destroy a US-bound airliner using a bomb which could have been undetectable by conventional airport scanners.

A would-be suicide bomber tasked with bringing down the passenger jet was in fact a double agent, recruited by Saudi intelligence and in possession of a British passport.

In a separate development, Yemeni military officials said an assault by government troops Saturday on al-Qaida forces around the southern city of Zinjibar left a general, a soldier and six militants dead.

The attack was part of the republic's broader campaign against al-Qaida-linked fighters in the south. Residents say the military used warplanes and artillery to pound areas west and north of Zinjibar.

All officials spoke on condition of anonymity in line with military regulations.